Trolleys with swiveling castor wheels are generally heavy and unwieldy to steer and are particularly difficult to control when they are loaded. Maneuvering a trolley utilizing the handrail provided at the rear of the trolley is no easy task, and involves a certain degree of dexterity and strength from the arm, waist and back of the user.
Users often find themselves in circumstances where they need to change the direction of travel of the trolley frequently such as when maneuvering a shopping trolley along an aisle in a supermarket. The same applies to trolley beds in hospitals and serving trolleys in restaurants and bars. When turning a trolley from standstill, the user effectively acts as the pivot about which the trolley is moved. As the front castor wheels are relatively distant from the user, a significant torsional force from the waist and lower back of the user is required in order to turn the trolley from standstill or to swing it around from the direction it is pointing. The force required for this is substantially increased when the trolley is loaded. As a result, lower back injuries and muscle strain are relatively common. The resulting muscle pain and discomfort may not be immediate, but may become apparent hours or days after trolley usage. In severe cases, muscle injuries resulting from trolley usage may exacerbate existing muscle or spine injury and in some cases, can be debilitating.
Also, an awkward situation in which users quite frequently find themselves is when pushing a trolley across a sloping or uneven surface. Trolleys are inherently susceptible to turning down a sloping surface, in which instance, the user is forced to exert a significant effort in order to maintain the trolley on track. The user must exert a constant torsional force from their back region to prevent the trolley from turning from the direction of travel while traversing the sloping surface, which again subjects the user to increased risk of back and muscle injury.
It is the ideal for trolleys that they be configured so as to make them both steerable and otherwise maneuverable. Trolleys are typically fitted with swiveling castors as the swiveling action of the castors makes the trolleys readily maneuverable. As such they can be maneuvered sideways and in any-which-way which makes them very useful in narrow, confined spaces and crowded areas. The swiveling castors are frequently used in combination with fixed wheels/castors as the fixed castors provide a degree of guidance to enable better and easier steering. Typical to the group of trolleys concerned are supermarket trolleys, platform trolleys, warehousing trolleys, prams and pushers, and trolley beds.